No Horizontal Sync

[Jonathan]

I finally got the missing tubes I needed and got a raster on my 630TS chassis, but it's out of horizontal sync. No adjustments seem to fix the problem, I've tried all the controls. What should I start troubleshooting first? The only thing I can think of, is that I installed the wrong value replacement capacitor, miswiring, or a bad tube. Attached are pictures of what it looks like. Sound works and everything else seems to work.

Thanks.

Jonathan

[Eric H]

It looks more like a frequency problem rather than a sync problem at this point, the oscillator is probably running too slow.
Did you adjust the Horiz Freq coil? I believe it's on the back apron on the 630 but some RCA's have it underneath the chassis on the inside.
This is an adjustable slug rather than a Potentiometer.

Do you have the Sam's on it? If you do try running the Horizontal alignment procedure.

Next guess would be that you did install a wrong value part somewhere, possibly a .001 where a .01 is called for, double check your work around the Horiz Osc tube and Sync Separator tube, also around that frequency coil.
Also a resistor in the Horiz circuit that has drifted way up in value can cause this.

Sometimes I'll just jump another .01 cap across the caps in the horizontal section till I find one that changes it drastically, that can help narrow it down quickly.

[jeyurkon]

I agree with Eric in that it looks like the horizontal frequency is too low.

When you said you tried all of the controls, did that include the horizontal frequency control on the rear? Someone may have screwed it all the way in.

The Rider's for this is on the ETF site and is very comprehensive.

I'd check R198, R231. And if you replaced C168 0.015 uF, make sure you used the right value, it's critical.

V124, 6AC7, is used as a variable reactance to control the horizontal frequency and if anything is wrong in that circuit it can cause a problem also.

The Rider's gives instructions for aligning the horizontal section. Tedious, but straightforward.

John

[Phil Nelson]

I noticed an old post where you mentioned replacing "micamold" capacitors. The Micamold company made both mica and molded paper caps with that brand name (http://antiqueradio.org/recap.htm). If you replaced micas, then various things like this may need tweaking. Should not be a problem if you used exact values.

If you get bored with Riders, you can also download the RCA service manual from http://www.antiqueradio.org/RCA630TSService.pdf . The 630TS is better documented than just about any vintage TV.

The pics you posted look pretty encouraging. Who knows, maybe after you adjust the horizontal frequency, the picture will just pop in.

Regards,

Phil Nelson

[jeyurkon]

Don't listen to jeyurkon, he doesn't know what he's talking about.

I meant to say C169, not C168. Check them both anyway.

John

[Jonathan]

Thanks guys! I checked my capacitors and they are all correct. I have both the Riders and the RCA service data. My 630TS does not have C164, but C169 is right as well as C168. R210 and R158 are both 6.8k resistors, though are both drifted to 8k. R158 seems connected to the plate and screen of the sync separator 6SH7 and R210 is connected to the horizontal drive. A drift from 6.8k to 8k is quite a drift, but not as bad as I've seen. I suppose these should be replaced?

After finding these resistors, I powered up the set again. T108 was the only control I did not adjust, as well as horizontal width coil in the HV cage. Adjusting T108, I was able to get a recognizable picture, but still out of sync that rolls sideways. Attached are latest pictures. The pictures are of DW-TV's Journal.

Thanks.

[DaveWM]

6AL5 is ok right?

[DaveWM]

wow I just looked at that service manual, that is one tube hungry set.

I was thinking V123. I noticed there were some jumpers that allowed for unstable sync etc...

[jeyurkon]

Originally Posted by DaveWM

wow I just looked at that service manual, that is one tube hungry set.

I was thinking V123. I noticed there were some jumpers that allowed for unstable sync etc...

Right, he could try moving the jumper on J-102 to positions 1-2 and see if that helps.

John

[ChuckA]

If everything else checks OK make sure you have filament voltage to the 6AL5 (V123). This filament has a 2.2 ohm resistor in series and the first set I had sync problems with drove me nuts till I noticed the tube wasn't lit.

Chuck

[cbenham]

Originally Posted by ChuckA

If everything else checks OK make sure you have filament voltage to the 6AL5 (V123). Chuck

In a similar vein, check the 6AC7 H. control tube to see if it's warm. The one in my set would come and go; turned out that a filament lead wire inside the tube pin was loose and resoldering it made it work reliably. I resoldered all the tube pins actually. Tried all kinds of imaginary fixes before finding the tube was cold!
Or just try another 6AC7 and make sure the tube socket contacts are good as well.

A great engineer told me once, "Look for the broken wire, not the third harmonic!"

Cliff

[jeyurkon]

Originally Posted by ChuckA

If everything else checks OK make sure you have filament voltage to the 6AL5 (V123). This filament has a 2.2 ohm resistor in series and the first set I had sync problems with drove me nuts till I noticed the tube wasn't lit.

Chuck

That's a good point. The one in my Sylvania was bad too. It was one of those early wire-wound types.

I think they do this so that the 6AL5 warms up more slowly than the rest of the tubes. Otherwise, it could lock in on a harmonic of the horizontal frequency.

John

[kx250rider]

Originally Posted by jeyurkon

I'd check R198, R231. And if you replaced C168 0.015 uF, make sure you used the right value, it's critical.

V124, 6AC7, is used as a variable reactance to control the horizontal frequency and if anything is wrong in that circuit it can cause a problem also.

YES! That's the tricky part of all early RCA sets. Although I didn't check the location numbers in the 630, the cap that sits across the horizontal oscillator coil should be a mica cap, and needs to be the exact value, and 5% tolerance if possible.

Charles

[Jonathan]

The 6AL5 and 6AC7 are both hot. I swapped the 6AL5 with other tubes in the set and I got the same result. The capacitor across the horizontal frequency transformer is 0.015uF, labeled "503K" and is a new plastic capacitor which replaced the old paper capacitor in it's place. I think the best I can do now is scour the horizontal sections for drifted resistors. Two of the 6.8k resistors I found were drifted to 8k, both part of the horizontal circuit, so I'll keep searching there and for any mistakes I made. Thanks guys, I'll keep you posted!

[Giulio Maiocco]

Hello Jonathan,

I just hope your "503" capacitor is a typo, as if this is what you used to replace the original 0.015uF capacitor, you are way off, 503 means a 0.05uF cap!

Cheers

Giulio